Raman spectroscopy, a vibrational spectroscopy technique, is an analytic tool for probing molecular and biological structures and understanding the chemical properties. The highly structured, information-rich Raman spectra, like fingerprints, can be used to identify wide range of chemical compounds and materials. For example, this technique has been used to identify hazardous materials and contraband drugs, and for monitoring chemical manufacturing processes and for pharmaceutical drug development.
Raman spectroscopy has several distinct advantages over other analytical tools such as infrared (IR) spectroscopy and gas/liquid chromatography (GC/LC). The most important advantages include the fact that it: 1) is a non-invasive and non-destructive technique, 2) can avoid sample preparation, and 3) can be used for aqueous samples. In comparison, GC/LC can only be used for liquid and gas materials, and it utilizes a destructive sampling technique by extracting samples that are sent through separation columns. Furthermore, the sampling and identification time of the GC/LC method is typically several minutes, which is not suitable for many applications.
Infrared (IR) spectroscopy provides similarly information-rich spectra like Raman spectra by probing the vibrational states of molecules. Its big drawback, however, is that IR spectroscopy cannot be effectively used for aqueous samples due to strong water absorptions; even for many other materials it requires preparation of thin samples. These comparisons make the Raman spectroscopy the preferred technique for many substance identification or diagnostic applications that require field autonomous, non-contact, non-invasive or non-destructive characteristics and can identify a diverse range of materials.